Young female sexual minorities (YFSM) are at exceptionally high risk for intimate partner violence (IPV), with over half of YFSM reporting physical or sexual abuse by a dating partner. These young IPV victims may be particularly vulnerable to the negative physical and mental health consequences of IPV, including substance abuse, depression, and suicide, due to minority stress and diminished protective resources (e.g., parent support, community connectedness). In addition, YFSM may be less likely to report and to seek or receive help for IPV because they are not out about their sexual orientation or they fear stigmatization and discrimination. Women who seek help for same-sex IPV are often denied services (e.g., two-thirds of LGBT IPV survivors were denied access to domestic violence shelters) and feel marginalized and unsupported by domestic violence service systems. Basic research is clearly needed to inform development of culturally sensitive, evidence-based interventions to prevent IPV in YFSM and to support female sexual minority IPV victims. The existing literature, however, has almost exclusively focused on IPV in heterosexuals. Because LGBT teens and young adults face unique issues surrounding their relationships and sexual behaviors (e.g., pressures to deny or conceal sexual identity and activities), the risk and protective factors for IPV, help-seeking behaviors, and consequences of IPV in sexual minority youth are likely quite different from those observed in heterosexual youth. The overarching goal of this project is to begin to address these disparities by conducting an innovative study of IPV in female sexual minority adolescents and young adults (YFSM). We propose a novel, minority stress-informed dynamic developmental systems perspective of IPV in YFSM, which we will test using a mixed-methods, accelerated longitudinal design. Building upon the longest running study of LGBT youth, we will collect quantitative data from two ethnically diverse cohorts of YFSM (N= 530; ages 16-26) every six months for two years, as well as qualitative data from 50 selected participants. We will accomplish the overarching goal with four primary specific aims: (1) Describe the nature and trajectories of IPV in YFSM across adolescence and young adulthood; (2) Identify risk and protective factors for IPV among YFSM, including factors that differentiate violent vs. non-violent/healthy relationships; (3) Examine factors that affect YFSM's reporting of IPV, help-seeking for IPV, and ability to benefit from help provided (e.g., cultural competence of providers); and (4) Evaluate the consequences of IPV in YFSM, identifying factors that raise risk for or protect YFSM victims from revictimization and negative health consequences of IPV. Integration of the resulting quantitative and qualitative data will be used to inform the development of evidence-based interventions to prevent IPV among YFSM and better serve those who experience IPV. 1